Means for the radio-translation of phonographically-recorded sound waves



' F. THORINGTON MEANS FOR THE RADIO TRANSLATION OF PHONOGRAPHICALLY RECORDED SOUND WAVES Filed Dec. 30, 1927 s Sheets-Sheet 1 1. 3 2. z lllllllll/ 7 s 6 27 1 i "1 E z a 38 25 Z 2 5 '23 5 5 31 L 3 I i 2! 5 5 4 2 1o 5 g 12 A I A? IIIIIII/I f/e fa/rer Tbor/hgfon,

INVENTOR.

' BY M W ATTORNEYS.

Oct. 30, 1928. 1,689,564

a F. THORINGTON MEANS FOR THE RADIO TRANSLATION OF PHONOGRAPHICALLY RECORDED SOUND WAVES A Filed Dec 30, 1927 3 Sheets-Sheet 2 f/efaher' Thar/n5 for),

INVENTOR. IV/fne we dazifliim BY r I, v I I I 4 ATTORNEYS.

Oct. 30, 1928. I 1,689,564

- F. THORINGTON MEANS FOR THE RADIO TRANSLATION OF PHONOGRAPHICALLY RECORDED SOUND WAVES Filed Dec. 30, 1927 3 SheetsSheet 3 I flefaher' Marnzzfig ATTORNEYS.

Patented Octa 30, 1928.

UNITED STATES FLETCHER THOR-INGTON, OF BIRMINGHAM, ALABAMA.

MEANS FOR THE RADIO-TRANSLATION OF PHQNOGRAPHICALLY-REGORDED SOUND WAVES.

Application filed December 30, 1927. Serial No. 243,611.

This invention relates to an improved apv ment in the unitof such an apparatus which is known in the art as a pick-up.

Heretofore pick-up units have been of either of two types, namely the ncapaclty type and the magnetic type, but it has been found that each of these types of pick-ups has deficiencies, peculiar to the particular type of pick-up, which it is the primary object of the present invent-ion to overcome.

Pick-ups of the capacity type present the disadvantage that, while the low frequencies are reproduced with remarkable trueness as to tone, the high frequency waves are inadequately amplified, and, on the other hand, in'the use of a pick-up of the magnetic type, the high frequencies are reproduced with a remarkable trueness of tone, but the low frequencies are not reproduced with the same effect as where a pick-up of the capacity type is employed. Inasmuch as a faithful reproduction of tones representative of both high and low frequencies, is essential, if the reproduction is, on the whole, to be true to the recorded tones, the present invention contemplates the provision of a pick-up unit embodying a combination of the principles of both the capacity and magnetic types of pick-ups. Therefore the present. invention contemplates the provision of means whereby recorded sound waves may be reproduced with a degree of accuracy which isnot obtainable by the employment of pick-up units of the types referred to above.

While the accompanying drawings and the description which is to follow, constitute a disclosure of the preferred embodiment of the invention, it will be understood that various changes may be made within the scope of what is claimed.

In the accompanying drawings:

Figure 1 is a view in front elevation of the pick-up unit embodying the invention, the casing of the unit being shown in Vertical section;

Figure 2 is a vertical transverse sectional View through the unit;

Figure 3 is a horizonta'lsectional view taken substantially on the line 33 of Figure 2 looking in the direction indicated by the arrows;

Figure 4- is a view in side elevation of the unit, the right hand side of the casing shown in Figures 1 and 2 being removed;

Figure 5 is a similar view of the unit, the opposite side of the casing being removed and parts which are immediately connected thereto being shown in section;

Flgure 6 is a horizontal sectional view taken substantially on the line 66 ofFigure 4 looking in the direction indicated by the arrows;

Figure 7 is a detail vertical transverse sectional View through a portion of the unit;

Figure 8 is a similar view through another portion of the unit;

Figure is a diagrammatic View illustratmg a rectifylng and amplifying circuit in which the unit may be employed.

The parts comprising the pick-up embodying the invention are housed within a casing which is indicated in general by the numeral 1 and which is preferably of aluminum or other non-magnetic metal and likewise preferably formed in two sections indicated by the numerals 2 and 3, one of these sections, as for example the section 2, being provided upon lts outer face, with a socket member 4 adapting the casing to be mounted upon the tone arm of a phonograph. The casing sections may be held in assembled relation by any appropriate means such for example as cross rods 5, and, for a purpose to be presently explamed, a supporting bracket 6 is either integrally connected or is secured at its lower end to the inner side of one section of the casing, as for example the said section 2, and at a point suitably spaced above the open lower end of the casing and extends upwardly substantiallyparallel to the said casing section and is provided at its upper end with an inwardly directed arm indicated by the numeral 7, this supporting bracket being likewise of aluminum, in the preferred embodiment of the invention.

As before stated, the present invention contemplates the utilization of the principles involved in both the magnetic and capacity types of pick-ups, and as illustrated in the drawings a permanent horse shoe magnet 8 is'supported within the casing 1, preferably by the cross rods 5, which are of non-magnetic metal or other material suitable for the purpose, and the arms of the magnet 8 support pole pieces which are indicated by the numeral 9 and which are preferably secured at lio their relatively remote ends to the relatively opposite sides of the respective arms 8 of the magnet and extend laterally inwardly from the respective arms in parallel relation to each other and are preferably provided with inward extensions indicated by the numeral 10, the opposing sides of the pole pieces, be-

tween the extension of each pole piece being recessed as at 11 to accommodate a coil 12 the terminals of the, winding of which are connected to suitable binding posts 13 suitably mounted upon the wall of the casing sect-ion 2, the pole pieces and coil 12 being supported in symmetrically arranged positions with respect to the lower ends of the arms of the magnet 8. The electro-magnet, of which the coil 12 constitutes the field or winding, has, as its armature, a soft iron plate 14 which is embedded in the relatively narrow down.- ward extension 15 of an aluminum plate 16 which is preferably of the rectangular form shown most clearly in Figure 4 of the drawings and which constitutes one plate of a condenser which will presently be more specifically described, and bv reference to Figures 2, 4 and 6 of the drawings it will be observed that the said extension 15 of the plate 16 extends downwardly through the core of the coil 12 in concentric relation thereto with the armature 14 located intermediate and opposite the extensions 10 of the pole pieces 9 of the permanent horseshoe magnet 8. The aluminum condenser plate 16 is provided at its upper edge with a short vertical extension 17 from the upper end of which projects a stud 18 having a substantially spherical head 19 which is disposed within a correspondingly formed socket 20 in a block 21 of rubber, the opposite sides of this block being disposed in recesses 22 formed in the two members 23 of a clamp, and the neck 18 depending between the opposing edges of the bottom walls of the recesses 22 as clearly shown in Figure 7, so as to provide for the necessary vibratory movement of the plate 16 under conditions which will presently be explained. The clamping members 23 are adapted to be adjusted and held assembled by means of an adjusting screw 23 as best shown in Figure 7. The two clamp members 23 are supported by depending branch leaves 24 of the leaf spring 25 which is anchored at its upper end in a socket 26 provided in the bracket arm 7 a set screw 27 being threaded into the end of the arm and bearing at its inner end against the said spring so as to support the spring and in turn provide for suspension ofthe clamp comprising the members 23, in position to suitably suspend the condenser plate 16. In order that the clamp may be adjusted so as to provide for accurate positioning of the condenser plate 16 with respect to the fixed plate of the condenser unit of which it constitutes the movable plate, and likewise to provide for accurate centering 0f the armature 14 in the air gap between the extensions 10 of the pole pieces 9 of the magnet 8, an adjusting screw 28 is fitted through an opening 29 in the bracket member 6 and threaded into a socket 30 formed in the clamping member 23 which is next adjacent thereto. The adjusting screw 28 is arranged with its head in engagement with the outer side of the bracket 6, and the shank of the screw extends through a spacing and backing member 31 which is of rubber and which is interposed between the said one of the clamping members 23 and the said bracket 6.

The fixed plate of the condenser unit is indicated by the numeral 32 and is preferably of brass and is mounted upon a supporting and backing plate 33 which is preferably of fiber, this plate being mounted by screws 34, upon arms 35 which extend laterally from the bracket 6. A conductor wire 36 is electrically connected with the fixed condenser plate 32 to a binding post 37 upon the wall of the casing section 2, a binding post 38 being also arranged upon the said Wall of the easing section 2, and a conductor wire 39 being connected with this post and with the movable condenser plate 16.

In order that the extension 15 of the condenser plate 16 may be properly centered and yieldably maintained in position directly axially of the core of the electromagnet 12 and with the armature 14 located midway of the air gap between the pole piece extensions 10. a collar 40 of insulating material is arranged upon the said extension 15 immediately below the said electromagnet 12, and a second collar 41 is disposed within a groove 42 formed circumferentially in the collar 40 and strands of resilient wire 43 are extended from the said collar 41, in opposite directions, and are provided at intermediate points with coils 44 to increase their resiliency, and are anchored at their ends as at 45 to the wall of the casing sect-ion 2.

The said extension 15 of the condenser plate 16 is provided with a socket 46 in its lower end into which may be re-movably fitted the shank of a stylus 47 of the ordinary type which is to travel in the record groove of the phonograph record which is to be reproduced. the stylus being held in place by the usual set screw indicated by the numeral 48.

A typical radio receiving circuit in which the pick-up embodying the invention may be employed, is illustrated diagrammatically in Figure 9 of the drawings, and in this figure the numeral 49 indicates acoil which is arranged in inductive relation to the primary winding 50 of an inductance 50, the secondary winding of which is indicated by the numeral 51. A wire 53 is led from the fixed plate 32 of the capacity unit of the pick-up to one terminal of the coil 49, and a wire 54 led from the other terminal of this coil to one terminal of the primary winding 55 of an untuned radio-frequency transformer indicated by the numeral56, a conductor wire 57 being led from the other terminal of the primary 55 of said coil to the movable plate 16 of the said capacity unit. A conductor wire 58 is led from one terminal of theprimary 50 of the inductance 50 to the negative filament leads of the oscillator and detector tube-s of the receiving apparatus, which tubes are indicated respectively by the numerals 59 and 60. The other terminal of the primary 50 of the inductance 50 is placed in the cir cuit, by a wire 61, with the grid 62 of the tube 59, and one terminal of the secondary 51 of the inductance 50' is in circuit with the plate of the tube 59 through a conductor wire 63, the other terminal of the secondary 51 being connected by a wire 64.- tothe primary 65 of an audio-frequency transformer 66' and to the positive terminal of the B-batter-y input as shown in Figure 9. As illustrated in the said figure, a fixed condenser 67 is shunted across the wires 58 and 61 leading from the termi-- nals of the primary 50 of the inductance 50. The secondary of the untuned radio-frequency transformer 56, indicated by the numeral 68, has one terminal connected by a wire 69 with the negative terminal of the C- battery employed in connection with the apparatus, which battery is of a strength to supply suflicient C voltage to cause the tube 6.0 to operate on the lower bend of its characteristic curve, and a conductor wire 70 leads, from the other terminal of the secondary 68 to the grid 71 of the tube 60, and a variable resistance 72 is in shunt with the wires 69 and 70 and serves as a means whereby the output of the circuit in which the capacity unit of the pick-up, comprising the fixed andvmovable condenser plates 32 and 16 respectively, may be controlled. I

A conductor wire 7 3 is connected with one of the binding posts 13 and consequently electrically connected with one terminal of the electromagnetic coil 12, and leads to the other terminal. of the primary 65 of the audio-frequency transformer 66, and a conductor wire 74 is connected tothe binding postfor the other terminal of the coil 12 and to the plate of the. tube 60, a variable resistance being placed in shunt with the conductor wires 73 and 74 so as to provide means for controlling the output of the circuit in which the electromagnetic unit of the pick-up is located. A by-pass condenser 74 is in shunt with the conductor wire and the positive side of the B- battery input. 7.

From the foregoing description of the pickup it will be evident that the member which comprises the movable plate 16 ofthe condenser constituting the, capacity unit of the pick-up and-the support for the armature 14' of the electromagnet 12 constituting the electromagnetic unit of the pick-up, is supported for vibratory movement by the resilient elements 24, the clamp comprising the members 23, and the bushing 21 which is, as previously stated, of ft rubber, so that, as the groove of the phon graphic record travel-s past the stylus 47, the said member comprising the movable condenser plate and armature support is laterally vibrated and the amplitude of the vibrations is varied in consonance with the undulations in the lateral walls of the record groove, it being understood that this vlbratory movement of the said member is sufficiently yieldably resisted by the bushing- 21, to avoid any undue amplification of the vibration.

By reference to Figure 9 it will be evident comprising the capacity unit, and inasmuch as vibration of the said member results in a consonant variation in the spacing of the movable plate 16 of the condenser with respect to the fixed plate 32 thereof, the variations in current flow in the primary 55 will be in consonance with the vibrations produced by variations in the contour of the undulations in the record groove. evident, at this point, that the vibratory It will be member of the pick-u is capable of a free-' dom of movement w ich is not obtainable in the case of the diaphragm of the reproducer of a phonograph, and, inasmuch as this member, in the instance of the present invention, is of aluminum and therefore exceptionally light in weight, and no appreciable impediment is offered to its vibratory movement due to the action of the undulatory side walls of the record groove upon the stylus, the member will respond to all of the delicate overtones as well as to the fundamental tones of the composition impressed in the record, and in this manner a faithful reproduction of the low frequencies of the musical scale is obtained. It will also be evident by reference toFigure 9 that the vibration of the vibratory member will effect a variation in the position of the armature-14 between the extensions of the pole pleces of the magnet and that, therefore, consonant variations in the magnetic flux which are thusproduced, will cause corresponding variations in voltage in the lead 74 between the 'electromagnet 12 and the plate of the tube 60 and these voltage variations will effect an exceptionally faithful reproduction of the high frequencies of the recorded composition.

As a consequence, due to the faithful reproduction of the higher frequencies through the medium of the magnetic unit of the pickup, and the correspondingly faithful reproduction of the lowerfrequencies through the 'cillating radio-receiving circuit, which circuit includes an inductance coil and a radiofrequency coll, an audio-frequency transformer, and tubes in circuit with the" said coils, said means comprising a vibratory element to be actuated by the undulatlons of a phonographic record groove, a capacity unit inductively in circuit with the oscillating coil of said circuit and in series with the primary of the radio-frequency coil of the circuit, the said unit comprising a fixed element and an element movable with the vibratory element, and an electromagnetic unit including a coil in circuit with the primary of the audiofrequency transformer of the circuit and with the plates of the said tubes of the circuit, said electromagnetic unit including an armature also movable with said vibratory element.

2. In a device of the class described, a vibratory element, means a carried thereby for supporting a phonographic stylus, a capacity unlt com rising a condenser plate fixedly supporte ii -juxtaposition to the said vibratory element and a companion condenser 1 plate supported in spaced relation thereto by the said vibratory element, and an electromagnetic unit comprising a coil and an armature supported by'said vibratory element in the field of the coil. L

3. In a device of the class described, a vibratory element, means carried thereby for supporting a phonographic stylus, a capacity unit comprising a condenser plate fixedly supported in juxtaposition to said vibratory element and a companion condenser plate supported in spaced relation thereto by said vibratory element, and an electromagnetic unit comprising a fixed magnet, a coil arranged between the pole pieces of the magnet, and an armature supported by said vibratory element in the field of the coil and betweenthe pole pieces of the magnet.

24. In a device of the class described, a sup port, a vibratory element, resilient means supporting the vibratory element from the support, means carried by the vibratory element or supporting a phonographic stylus,, a fixed condenser plate upon the support, a condenser I 7 plate movable with the said vibratory ele ment, a fixed magnet upon the support including spaced opposing pole pieces, a coil supported between said pole'pieces, and an arma ture support-ed by said vibratory element within the field of said coil and between the said pole pieces.

5. In a device of the class described, a support, a vibratory element, resilient means supporting the vibratory element from the support, means carried by the vibratory element for supporting a phonographic stylus, a fixed condenser plate upon the support. a condenser plate movable with the said vibratory element, a fixed magnet upon the support including spaced opposing pole pieces, a coil supported between said pole pieces, an armature supported by said vibratory element within the field of said coil and between the said pole pieces, and means for centering and maintaining the said armature in uniformly spaced relation with respect to the pole pieces and within the-field of the coil, comprising a resilient yieldable connection between said support and said element below the point of suspension of the element.

6. In a device of the class described, a support, clamp members, means resiliently supporting the clamp members beneath an extension of said support, a block of rubber interposed between the clamp members, a vibratory element having a head embedded in said block, whereby the member is suspended for vibration and its vibratory movement dampened, means carried by the element for the support of a phonographic stylus, a condenser unit comprising a fixed condenser element supportedin spaced relation to the vibratory element and a condenser element movable with the said vibratory element, a magnetic unit comprising a fixed magnet having spaced opposing pole pieces, a coil supported be- 7 tween the pole pieces, the said element having a portion extending in centered position within the field of said coil and between the pole pieces, and an armature supported by said portion of said element.

7. In a device of the class described, a support, clamp members, means resiliently supporting the clamp members beneath an exten sion of said support, means extending between one of said clamping members and said support for effecting adjustment of the clamping members with respectto the support, a block of rubber interposed between the clamp members, a vibratory element having ahead embedded in said block, whereby the member is suspended for vibration and its vibratory movement dampened, means carried by the element for the support of a phonographic stylus, a condenser unit comprising a fixed condenser element supported in spaced relation .to' the vibratory element "and a condenser element movable with the said vibratory element, a magnetic unit coming pole pieces, a coil supported between the pole pieces, the said element having a portion extending in centered position within the field of said coil and between the pole pieces and an armature supported by said portion of said element.

8. In a device of the class described, a support, clamp members, means resiliently supporting the clamp members beneath an extension of said support, means extending between one of said clamping members and said support for effecting adjustment of the clamping members with respect to the support, a block of rubberinterposed between the clamp members, a vibratory element havin a head embedded in said block, whereby 518 member is suspended for vibration and its vibratory movement dampened, means carried by! the element for the support of a. phonographic stylus, a condenser unit comprising a fixed condenser element supported in spaced relation to the vibratory element and a condenser element movable with the said vibratory element, a magnetic unit comprising a fixed magnet having spaced opposing pole pieces, a coil supported between the pole pieces, the said element having a portion extending in centered position within the field of said coil and between the pole pieces, an armature supported by said portion of said element, and means for yieldably maintaining the said portion of the said vibratory element in position to maintain the armature centrally within the field of the coil and between the pole pieces of the fixed magnet comprising a yieldable resilient connection between said portion of said element and the support. r

In testimony whereof I afiix my signature.

FLETCHER THORINGTON. 

